The present invention relates to a fire-resistant sheet-like molded article suited for use in fields where heat insulation and fire-resistant properties are required, in particular for use as a building material, to a fire-resistant laminate for covering a structural steel and a fire-resistant structural material for wall in which said molded article is used, and to a method of fabricating a fire-resistant structural steel and a fire-resistant wall.
In the field of building materials, flame retardancy has been required under the Building Standards Act and other regulations. On the other hand, a resin material has come into wide use in the building industry with the recent development of new uses and, accordingly, a fire-resistant resin material has been demanded.
Such a fire-resistant property includes not only the flame retardancy of the resin material itself but also its capability to prevent propagation of flames on the face side to the reverse side. The resin components and organic components in a resin material are inherently combustible and/or meltable and, therefore, it is an important performance requirement to keep them from combusting or melting for a sufficiently long period of time.
Thus, various technologies of compounding an inorganic component for providing flame retardancy have been proposed. However, an inorganic component lacking in self-adhesion properties tends to drop off, with the result that flames are allowed to propagate round to the reverse side. It is therefore a problem to be solved how to maintain the shape without such drop-off for a sufficiently long time.
In Japanese Kokai Publication Hei-06-25476, there is disclosed a resin composition comprising a polyolefin resin supplemented with red phosphorus or a phosphorus compound as well as thermally expandable graphite. This resin composition has sufficient flame resistance, indeed, from the oxygen index viewpoint but, when molded into a sheet and used as a wall backing, for instance, it cannot meet the flame retardancy or fire protection test requirement that when the face side is heated to 1,000xc2x0 C., the temperature of the reverse side should not rise over 260xc2x0 C.; it is thus insufficient in flame retardancy. Furthermore, in the flame retardancy or fire protection test, fragile residues alone remain and others drop off, so that the functionality as a heat insulation layer is lost at an early stage, which is another problem.
A resin composition comprising a urethane resin, ammonium polyphosphate and thermally expandable graphite has been proposed as an expansion material for fire-resistant joints. However, this is used to prevent the propagation of flames through around fire doors or joints of decorative panels, and the range of application is thus restricted. In addition, it has a problem, i.e. because a two-component curing method is employed, the technology is not called expedient, and the workability is poor because of the lack of tackiness.
A resin composition comprising a chloroprene polymer and vermiculite has also been proposed as a fire-resistant material. This is used to fill up gaps around the portions of walls or floors through which cables, ducts and the like are routed in the fire area to thereby prevent flames from spreading. The range of its application is thus restricted. Another problem is that its workability is poor because of the lack of tackiness.
A coat in composition comprising a binder resin, ammonium polyphosphate, an alcohol and a blowing agent has been proposed as a thermally expandable fire-resistant coating composition. However, this is rather suited for application to structures whose appearance is required to be decorative. In applications where any decorative character is not required but much importance is attached to fire-resistant properties, said composition cannot be considered suitable. Furthermore, since this is in the form of a coating, its workability is poor and, for providing sufficient fire-resistant properties, it is necessary to apply said composition in a considerable thickness and a technique therefor is required.
In view of the foregoing, the present invention has for its object to provide a fire-resistant sheet-like molded article having flame resistance and capable of producing good fire-resisting properties as the result of residues after combustion having sufficient shape-retaining property and, further, having good workability, a fire-resistant laminate for covering structural steels and a fire-resistant structure for walls in which said molded article is used as well as a method of fabricating a fire-resistant structural steel and a fire-resistant wall.
In accordance with a first aspect of the present invention, there is provided a fire-resistant sheet-like molded article comprising a resin composition and having the relationship between the initial thickness t (mm) and temperature difference xcex94T (xc2x0 C.) between one side and the reverse side after heating of said one side at 500xc2x0 C. for 1 hour as represented by:
xcex94Txe2x89xa70.015t4xe2x88x920.298t3+1.566t2+30.151t, and
having the initial bulk density at 25xc2x0 C. of 0.8 to 2.0 g/cm3 and the bulk density after 1 hour of heating at 500xc2x0 C. of 0.05 to 0.5 g/cm3.
In accordance with a second aspect of the invention, there is provided a fire-resistant sheet-like molded article comprising a resin composition, and having a breaking point and the load at breaking point of not less than 0.05 kg/cm2 when it is subjected to volume expansion by heating under radiant heat flux of 50 kW/cm2 for 30 minutes and then the combustion residue is compressed at a rate of 0.1 cm/s.
In accordance with a third aspect of the invention, there is provided a fire-resistant sheet-like molded article comprising a resin composition and showing the thermal conductivity, after the volume expansion by heating under radiant heat flux of 50 kW/cm2 for 30 minutes, of 0.01 to 0.3 kcal/mxc2x7hxc2x7xc2x0 C.
In accordance with a fourth aspect of the invention, there is provided a fire-resistant sheet-like molded article comprising a resin composition and showing the total endothermic value, when raising the temperature to 600xc2x0 C. at a rate of 10xc2x0 C./min. by DSC, of not less than 100 J/g.
In accordance with a fifth aspect of the invention, there is provided a fire-resistant sheet-like molded article comprising a resin composition and having an initial thickness of 0.5 to 20 mm and tackiness enough to support itself under a load of 15 to 40 N/m of width at not more than 180xc2x0 C. for 30 minutes or longer.